Cognato Anthony I, Hoebeke E Richard, Kajimura Hisashi, Smith Sarah M
Department of Entomology, Michigan State University, 288 Farm Lane room 243, East Lansing, MI 48824.
Museum of Natural History and Department of Entomology, University of Georgia, Athens, GA 30602.
J Econ Entomol. 2015 Jun;108(3):1129-35. doi: 10.1093/jee/tov073. Epub 2015 Apr 16.
Exotic insects are constantly intercepted at U.S. ports-of-entry. Of these, wood-boring beetles, particularly xyleborine ambrosia beetles, are sometimes missed during port inspections and become established in the United States. Euwallacea validus (Eichhoff) and Euwallacea interjectus (Blandford) are morphologically similar Asian ambrosia beetle species that vary by their fungal associates and their potential to cause economic damage. Euwallacea validus and E. interjectus were first discovered in New York (1975) and Hawaii (1976), respectively. Euwallacea validus was collected multiple times from widely separated localities and is assumed to have spread throughout the eastern United States. The discovery of E. interjectus in Florida (2011) and Texas (2011) prompted our review of the E. validus specimens because of the potential misidentification of the species. In addition, using mitochondrial cytochrome oxidase I (COI) DNA data and phylogenetic analysis, we tested the hypothesis that multiple introductions account for the U.S. populations of E. interjectus and E. validus. Our review of 7,184 specimens revealed an earlier introduction to the mainland for E. interjectus, which was first collected from Louisiana in 1984. This species is distributed in the South while E. validus occurs in the North with a known area of syntopy in northeastern Georgia. The extent of the syntopy within the United States is unknown and further investigation is required. Phylogenetic analysis of 24 E. interjectus and 20 E. validus individuals resolved clades that associated with each species and gross geographic provenance. Four well-supported clades represented E. interjectus which included the following localities: 1) Hawaii and Thailand; 2) Vietnam, Taiwan, and Texas; 3) Okinawa (Japan); and 4) Japan and several southern U.S. states. One clade comprised all E. validus specimens from Japan and the mainland United States. Four and two haplotypes were found for the E. interjectus and E. validus specimens, respectively, in mainland United States. Except for the Texas specimen, the haplotypes differed by one nucleotide. The relationship of the haplotypes and their sequence similarity suggested that the provenance of E. validus and the majority of E. interjectus haplotypes was Japan while the Texas haplotype originated later and from a location near Taiwan. Given the high nucleotide sequence difference between the Hawaiian and Thai haplotypes, the exact origin of the Hawaiian E. interjectus is unknown but likely Southeast Asia. A broader investigation including more SE Asian individuals will help to further explain the introduction of E. interjectus into Hawaii and Texas.
外来昆虫不断在美国入境口岸被截获。其中，蛀木甲虫，尤其是长小蠹科粉蠹虫，有时在口岸检查时被漏检，并在美国定殖。瓦氏长小蠹（Euwallacea validus (Eichhoff)）和间色长小蠹（Euwallacea interjectus (Blandford)）是形态相似的亚洲粉蠹虫物种，它们因共生真菌及造成经济损害的潜力而有所不同。瓦氏长小蠹和间色长小蠹分别于1975年在纽约和1976年在夏威夷首次被发现。瓦氏长小蠹在多个相距甚远的地点被多次采集到，据推测已扩散至美国东部各地。2011年在佛罗里达州和得克萨斯州发现间色长小蠹，促使我们对瓦氏长小蠹标本进行复查，因为存在物种误认的可能性。此外，我们利用线粒体细胞色素氧化酶I（COI）DNA数据和系统发育分析，检验了多次引入导致美国间色长小蠹和瓦氏长小蠹种群形成的假说。我们对7184份标本的复查发现，间色长小蠹更早被引入美国大陆，1984年首次在路易斯安那州采集到该物种。该物种分布在美国南部，而瓦氏长小蠹分布在北部，在佐治亚州东北部有一个已知的同域分布区。美国境内同域分布的范围未知，需要进一步调查。对24份间色长小蠹和20份瓦氏长小蠹个体的系统发育分析解析出了与每个物种及大致地理来源相关的进化枝。四个得到充分支持的进化枝代表间色长小蠹，包括以下地点：1）夏威夷和泰国；2）越南、台湾和得克萨斯州；3）冲绳（日本）；4）日本和美国南部几个州。一个进化枝包含来自日本和美国大陆的所有瓦氏长小蠹标本。在美国大陆，间色长小蠹和瓦氏长小蠹标本分别发现了4个和2个单倍型。除了得克萨斯州的标本外，单倍型之间相差一个核苷酸。单倍型的关系及其序列相似性表明，瓦氏长小蠹和大多数间色长小蠹单倍型的来源地是日本，而得克萨斯州的单倍型起源较晚，来自台湾附近的一个地点。鉴于夏威夷和泰国单倍型之间的核苷酸序列差异很大，夏威夷间色长小蠹的确切起源未知，但可能来自东南亚。包括更多东南亚个体的更广泛调查将有助于进一步解释间色长小蠹被引入夏威夷和得克萨斯州的情况。
